What is the recommended dose and frequency of gabapentin (Neurontin) for neuropathy pain?

Gabapentin Dosing for Neuropathic Pain

For neuropathic pain, gabapentin should be initiated at 100-300 mg at bedtime or 100-300 mg three times daily, gradually titrated to an effective dose of 900-3600 mg/day in 3 divided doses, with most patients requiring 1800-3600 mg/day for optimal pain relief. 1, 2, 3

Initial Dosing and Titration

• Start gabapentin at 100-300 mg at bedtime or 100-300 mg three times daily 1, 2
• Titrate gradually over several days to minimize side effects, with dose adjustments based on pain relief and tolerability 2
• A conservative titration schedule:
  • Day 1: 300 mg once daily
  • Day 2: 300 mg twice daily (600 mg/day)
  • Day 3: 300 mg three times daily (900 mg/day) 3
• Further increase by 100-300 mg every 1-7 days as tolerated until adequate pain relief is achieved 1
• Slower titration is recommended for elderly patients or those who are medically frail 2

Effective Dosage Range

• The effective dosage range for neuropathic pain is 900-3600 mg daily in divided doses 1, 2
• Initial target dose should be 1800 mg/day, as clinical studies have shown efficacy at this dose 4
• Doses up to 3600 mg/day may be needed in some patients for optimal pain relief 1, 5
• Higher doses (>1800 mg/day) are not consistently more effective than 1800 mg/day and are associated with more adverse effects 1

Administration Schedule

• The total daily dose should be divided into three administrations per day to maintain therapeutic levels 1, 2
• The maximum time between doses should not exceed 12 hours 3
• Three-times-daily dosing is particularly important at higher doses due to gabapentin's nonlinear pharmacokinetics (saturable absorption) 1

Dosage Adjustment in Special Populations

• Dose adjustment is required for patients with compromised renal function based on creatinine clearance 2, 3:
  • CrCl ≥60 mL/min: 900-3600 mg/day in three divided doses
  • CrCl 30-59 mL/min: 400-1400 mg/day in two divided doses
  • CrCl 15-29 mL/min: 200-700 mg/day as a single daily dose
  • CrCl <15 mL/min: 100-300 mg/day as a single daily dose 3
• Elderly patients may require lower starting doses and slower titration due to decreased renal function 1, 3

Duration of Treatment Trial

• An adequate trial of gabapentin requires 3-8 weeks for titration plus 2 weeks at maximum tolerated dose 1
• Full therapeutic effect may take up to 2 months to achieve 1

Monitoring and Side Effects

• Monitor for common adverse effects, which include:
  • Dizziness (19% of patients)
  • Somnolence (14% of patients)
  • Peripheral edema (7% of patients)
  • Gait disturbance (9-14% of patients) 5, 6
• Side effects are typically mild to moderate and often subside within approximately 10 days from initiation of treatment 4
• Starting with lower dosages and titrating cautiously can reduce the risk of dose-dependent dizziness and sedation 1

Clinical Efficacy

• About 38% of patients with diabetic neuropathy and 32% with postherpetic neuralgia achieve at least 50% pain relief with gabapentin at doses of 1200 mg/day or greater 5
• The number needed to treat (NNT) for at least 50% pain relief is 5.9 for diabetic neuropathy and 6.7 for postherpetic neuralgia 5
• Gabapentin is effective for various types of neuropathic pain, including burning pain, shooting pain, and allodynia 7, 8

Common Pitfalls to Avoid

• Inadequate dosing: Many treatment failures occur because patients don't reach therapeutic doses 4
• Too rapid titration: Can lead to increased side effects and treatment discontinuation 1
• Insufficient trial duration: Not allowing enough time for full therapeutic effect 1
• Failure to adjust dose in renal impairment: Can lead to toxicity 3
• Not dividing the daily dose: Gabapentin requires multiple daily doses due to its short half-life and saturable absorption 1